Phosphorus‐Containing C₁₂H₂₇O₄P as Functional Electrolyte Additives for High‐Voltage LiNi_0.5Mn_1.5O₄/Graphite Li‐Ion Batteries with Excellent Electrochemical Performance

Abstract

As the most promising cathode material in new energy resources, LiNi0.5Mn1.5O4 (LNMO) are widely researched due to its high platform, low cost, and environment‐friendliness, when they are assembled with graphite into battery which can lead to a faster capacity decay because of unstable solid–liquid interface. This work is devoted to stabilize electrolyte and protect interface of LNMO/graphite full battery by adding multifunctional additive, tributyl phosphate (TBP). Theory calculation which exhibits disconnection of TBP can participate in the reaction to form a uniform and dense cathode electrolyte interface film (8–10 nm) and solid electrolyte interface film around 15 nm on both electrodes, more importantly, the existence of phosphoric acid functional group can hinder the attack of hydrofluoric acid and protect electrode film. Besides, comparing with its homolog, the high‐voltage LiNi0.5Mn1.5O4/graphite battery with 1% TBP shows a preponderant discharged capacity retention of 77.8% after 150 cycles, while the blank is only 66%, this work provides a direction for electrolyte additives’ selection at high voltage and has far‐reaching significance for the application of phosphate ester materials.

Regulating the electrochemical reduction kinetics by the steric hindrance effect for a robust Zn metal anode

“…The TBP molecule consists of a single polar PO group and three hydrophobic butyl chains connected by ester bonds. 18 As shown in Fig. 1a, density functional theory (DFT) calculation demonstrates that the O atom in the PO group has more negative surface electrostatic potential (ESP) than the O atom in H 2 O, indicating stronger interaction between TBP and Zn 2+ .…”

Using Triallyl Phosphate as Electrolyte Additive to Stabilize Electrode–Electrolyte Interface of LiNi0.5Mn1.5O4/Graphite High Voltage Lithium Ion Cells

“…This shows that the deposit on the cathode is much less than that on the anode, which is consistent with the results in the literature. 18 Even so, at a higher magnification, it is still found that there is deposit on LNMO particles of the cycled TAP-free cell (Figure 2b (cathode)), while the surface of LNMO particles of the cycled cell with 1.0 wt % TAP is still clean (Figure 2d (cathode)).…”

“…A similar result has been observed in another work. 18 These deposits are believed to be caused by reduction of electrolyte and electrolyte oxidation products. However, the deposit on the surface of graphite anode from the cycled cell with 1 wt % TAP is much less (Figure 2c (anode)), and the surface of graphite particles is smooth and clean (Figure 2d (anode)).…”

“…The main function of additives is to form a coating layer on the carbon anode or LNMO cathode respectively through their electrochemical reduction or oxidation during the first several charge−discharge cycles of the battery. There are not many additives reported for the LNMO/graphite full cell, mainly including the following: lithium bis(oxalato) borate (LiBOB), 8 lithium catechol dimethyl borate (LiCDMB), 9 succinic anhydride (SA), 10 1,3propane sultone (PS), 10 tris(trimethylsilyl) phosphate (TMSP), 11 4-(Trimethylsiloxy)-3-pentene-2-one(TMSPO), 12 tris(1,1,1,3,3,3-hexafluoro-2-isopropyl)phosphate (HFiP), 13 3-(1,1,2,2-tetrafluoroethoxy)-1,1,2,2-tetrafluoropropane (F-EPE), 14 hexakis(2,2,2-trifluoroethoxy)cyclotriphosphazene (HFEPN), 15 biphenyl (BP), 16 lithium bis(trimethylsilyl) phosphate (LiTMSP), 17 tributyl phosphate (TBP), 18 etc. They can be divided into three categories: anodic SEI-forming additives (category 1), cathodic CEI (cathode electrolyte interphase)-forming additives (category 2), and bipolar CEI/ SEI-forming additives (category 3).…”

Real‐Time Mass Change: An Intrinsic Indicator to Dynamically Probe the Electrochemical Degradation Evolution in WO3

“…the electrochemical and electrochromic properties. The lithium ion (Li + )-based electrolytes have a vast array of applications, including electrochromic devices (ECDs), [1][2][3] batteries, [4] capacitors, [5] and so on. It is evident that the lithium-ion trapping in the host structure would result in an electrode degradation by direct or indirect electrochemical redox in electroactive support electrolytes, giving rise to irreversible electrochemical reactions.…”